1. Field of the Invention
This invention relates to X-ray spectroscopes incorporating analysing crystals and total reflection mirrors and used for fluorescent X-ray analyzing method or the like.
2. Description of the Prior Art
Fluorescent X-ray analysers usually incorporate analysing crystals for separating the characteristic X-rays of a substance to be detected, as mentioned in "Advances in X-Ray Analysis", Vol. 9, p. 497 (1967). In this case, it is in usual practice to provide a soller slit between the sample and crystal to let parallel X-rays be incident on the slit. Thus, in order to make effective use of X-rays having passed through the slit it is necessary to select the length l of the crystal to be above h/sin .theta. where h is the aperture height of the soller slit and .theta. is the angle of incidence of X-rays on the analysing crystal. If the incidence angle .theta. is too small, however, the crystal length l is extremely great, leading to reduction of radiation dose incident on the detector due to scattering in directions normal to the diffraction surface. Therefore, the efficiency of the spectroscope is reduced and too low to be able to make high precision analysis, and the device itself is liable to be extremely large in size. These drawbacks also apply in case of making ultra soft X-ray analysis by using total reflection mirrors.